The proposed investigation is to examine in detail the various factors and forces that govern the interactions of model proteins, whose detailed X-ray structure is known, and apply some of the findings using hydrophobic dissociating agents and salts as probes to proteins such as catalase, aldolase, actin, some of the high molecular weight hemoglobins and hemocyanins of invertebrate species, and complexes of double helical fragments of DNA and protamine. Light scattering molecular weight measurements represent the main technique to be employed. The study proposes both the testing of the utility of interaction constants (i.e., binding and Setschenow constants, and free energies of transfer) and equations used for the analysis of subunit dissociation data, and the development of new methodology to be utilized for light scattering investigations where only micro-quantities of materials are available. These studies are related to general problem of stabilization of tertiary and quaternary structure of biological macromolecules and their complexes, including such phenomena as the depolymerization of sickle hemoglobin gels and the inhibition of sickling of red blood cells by the alkylureas.